Those who muck with CFLAGS and COPTFLAGS be playing with dragons. Best to tread lightly, and carry a big stick.

listen to the man

-O or -O2 -fno-strict-aliasing are the only supported flags according to the documentation.

Unless you know exactly what you are doing, have read the compiler documentation, and are familiar with the code you will be compiling with them, do not screw with pre-set compiler options and expect things to work properly.